bug#41156: margins interfere with xterm-mouse-mode

[Eli Zaretskii]

> Date: Mon, 14 Jun 2021 22:29:36 -0700
> From: Jared Finder <jared@finder.org>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>, rudalics@gmx.at,
>  41156@debbugs.gnu.org, neil.okamoto@gmail.com
> 
> >> Jared, can you help us out here, please?
> > 
> > xterm-mouse-mode is running fine, it is correctly generating
> > mouse-motion events with proper X,Y coordinates.
> > 
> > The actual drag keybinding is handled in mouse-drag-line in mouse.el.
> > The following patch mostly works for me, though I see issues when
> > dragging to the left and the left buffer has a margin of width greater
> > than 1.  I think there's some incorrect logic in how the temporarily
> > bound move function is converting calculating positions:
> > 
> 
> And I'm fairly certain this is the proper fix.  If a window is live, 
> then the AREA-OR-POS made by posn-at-x-y should never be nil, I believe:

Thanks, Jared.

Lars, feel free to install, unless you have comments.